1. Field of the invention
The present invention relates to musical tone generating apparatuses for electronic musical instruments.
2. Prior Art
In general, electronic musical instruments have a musical tone generating apparatus which generates an amplitude envelope in response to operations applied to a performance operational member, for example a keyboard, and which generates a musical tone signal having an amplitude which is varied over time according to a generated amplitude envelope. FIG. 5 shows a waveform of an envelope generated by a conventional musical tone generating apparatus. In FIG. 5, KON designates a key-on time point at which a key of the keyboard is depressed, and KOF designates a key-off time point, at which the depressed key is released.
During a performance using a keyboard type electronic musical instrument, the same key may be repeatedly depressed within a short interval. In this case, the generation of the envelope corresponding to the second key-on event may be started before the envelope of the musical tone signal corresponding to the first key-on event has sufficiently attenuated. In many conventional musical tone generating apparatuses, when a new key-on event occurs, the envelope corresponding to the new key-on event is started at the predetermined initial value (FIG. 5 shows the case in which that initial value is [-60 dB]). Accordingly, there is a problem in that when plural key-on events repeatedly occur over time, the level of the current envelope suddenly drops to the predetermined initial value as indicated by mark KK in FIG. 5, thereby generating a click noise which is offensive to the ears.